Construction of concrete liquid reservoirs such as swimming pools



F. D. SPENCER SUCH AS SWIMMING POOLS .'5 Sheets-Sheet 1 Oct. l, 1968CONSTRUCTION OF' CONCRETE LIQUID RESERVOIRS Filed Feb. 2ll 1966 F. D.SPENCER UCTION 0F CONCRETE LIQUID RESERVOIRS Oct. 1, 1968 CONSTR FiledFeb. 2l, 1966 SUCH AS SWIMMING FOOLS 5 Sheets-Sheet 2 FIG.3

Oct. l, 1968 F. D4 SPENCER CONSTRUCTION OF' CONCRETE LIQUID RESERVOIRSSUCH AS SWIMMING FOOLS 5 Sheets-Sheet 5 Filed Feb. 2l, 1966 FIG 1......3 .w........o..6...o.

United States Patent O Mice 3,403,492 CONSTRUCTION OF CONCRETE LIQUIDRESER- VOIRS SUCH AS SWIMMING POOLS Francis Dudley Spencer, 51 NelsonRoad, Killara, New South Wales, Australia Filed Feb. 21, 1966, Ser. No.528,703 Claims priority, application Australia, Feb. 24, 1965,

f 55,584/ 65 3 Claims. (Cl. 52-744) ABSTRACT OF THE DISCLOSURE A methodof constructing a concrete liquid reservoir comprising the steps oflaying reinforcing tendons in the floor between opposite sides of thereservoir. End portions of the tendons are passed through bent anchoredguides bending them into the wall alignment. Intermediate portions oftendons which extend between a pair of guides are prepared to providefor slip between the portions and the concrete oor. The concrete is thenpoured to cover the intermediate portions of the tendons and the guide.The tendons are prestressed and the ends are supported while intensioned condition to insert stress to the oor. Then the concrete ispoured to form the walls around the end portions of the tendons. Theconcrete is cured and the support for the ends of the tendons is removedthereby transferring the stress in the tendons to the concrete walls inaddition to the oor of the reservoir.

This invention relates to the construction of concrete liquid reservoirsand more particular to swimming pools.

The present method of construction of such units involves the use oflarge amounts of reinforcing steel rods and concrete aggregate.

It is the main object of this invention to produce a swimming pool orother liquid reservoir, the main body of which is formed from concrete,which is considerably cheaper to produce than hitherto.

It is a furtherobject of the invention that the economy in constructionbe achieved through the application of the pre-stressing andpost-tensioning techniques to the present form of structural units.

To this end the invention provides a method of constructing a concretereservoir for liquids which has a oor and surrounding walls, comprisingthe steps of laying reinforcing tendons or rods in the floor between atleast a pair of opposite sides of the reservoir, passing end portions ofthe tendons through bent anchored guides so that they are bent into thewall alignment, preparing intermediate portions of the tendons whichextend between a pair of guides to provide for slip between saidportions and the subsequent concrete floor, pouring the concrete of theoor to cover the intermediate portions of the tendons and the guides,placing the tendons under tension, supporting the ends of the tendonswhile in a tensioned condition so as to impart stress to the floor,pouring the concrete to form the walls around the end portions of thetendons and allowing the concrete to cure and removing the support forthe ends of the tendons so that the stress in the tendons is transferredto the concrete walls in addition to the oor of the reservoir.

The invention also provides a swimming pool or other liquid reservoirconstructed according to the above method.

A preferred embodiment of the invention will now be described in whichthe constructional method is applied with respect to a swimming pool.Reservoirs of this kind may be of varied shape but in a conventionalsense they are substantially rectangular in plan with the four upright3,403,492 Patented Oct. 1, k1968 adjoining walls joined to the rim of aHoor tapering towards one end.

The properties of a strength and light-weight construction are wellknown for pre-stressed or post-tensioned concrete slabs. However, due toseveral diiculties in adapting for this purpose, pre-stressed and/orpost-tensioned slab have not been employed to the present time in theconstruction of swimming pools.

A preferred method of construction of the pool is illustrated in theaccompanying drawings, in which:

FIG. 1 is a fragmentary plan view of one end of the pool showing thedisposition of tendons within a ducting;

FIG. 2 is an elevation in longitudinal section of the part of the poolshown in FIG. l;

FIG. 3 is an enlarged view of the pool wall in vertical section;

FIG. 4 is a fragmentary perspective of the pool floor showing thetendons in place; f

FIG. 5 is a similar view showing the concrete blockwall constructed andthe tendons secured in stress to beams across the top of the Wall;

FIG. 6 is a similar view showing a further concrete wall poured withinthe cavity between the concrete block walls; and

FIG. 7 is a similar view showing the tendons cut off ilush with the topof the concrete wall.

The preferred method of construction of the pool is as follows. Asuitable bed of compacted sand 8 for the floor 10 of the pool is firstlyformed, over which is laid a layer of moisture-proof sheeting 9. Metaltubes or ducts 11 are positioned in parallel intersecting rows bothlaterally and longitudinally at the medial or neutral plane of the poolfloor 10. Tendons or rods 12, which may be single or multi strand, ofhigh tensile steel are then laid in the parallel lines of ducts 11extending across the width of the pool and longitudinally from end toend forming the matrix over which the concrete floor 10 willsubsequently be poured.

Guide sleeves 13 for individual tendons 12 comprise an arcuate tube,four of which are flared 4outwardly from the end of each duct 11. All ofthese sleeves 13 are laid fat spaced intervals around the rim 14 of thepool floor 10 so that with pouring of the concrete for the floor 10 theybecome embedded therein. Three stirrup rods 13A are located as stays foreach of the guides 13 (see FIG. 3). The tendons 12 have their endspassed through respective guides 13 located at opposite sides of thepool and are bent thereby through approximately so that the opposite endportions of each tendon extend in the neutral axis of the wall alignmentfor .the Pool.

A lubricant may be coated over the intermediate portions of all thetendons 12 which lie within the `respective guides 13 and ducts 11 inthe floor 10 of the pool. It is possible to omit the duets 11 and toprovide for sfuicient slip for the tendons Within the subsequentconcrete casing simply by the adjunct of lubricant. The next step in themethod is to pour 'the concrete for the floor 10 so that it covers boththe ducts 11 carrying the tendons as well as all of the guide sleeves13. This concrete is allowed to cure.

The wall construction is then commenced by the formation of a cavityblockwall 15, for example, of concrete blocks. The end portion of thetendons 12 extend upwardly through the cavity 16 rand beyond the end ofthe blockwall.

By expedient means each end of each tendon 12 passes through a metalbeam 17 which straddles the cavity 16 of the blockwall 15 and one end issecured fast to its respective beam 17 while by suitable jacks 18 andclamps 19 the other end of each 4tendon 12 is drawn taut and tensionedand locked in this position. It will be appreciated that the tendons 12vare free to move within the ducts 11 and guides 13 in the concretefloor through which they pass and the tensioning applied exertsconsiderable stress upon the blockwalls 15 and through these walls tothe floor of the pool to effect post-tensioning thereof.

Concrete is then poured into the cavity 16 of the blockw-alls -to alevel below Ithe upper end 21 of the blockwalls. After curing of theconcrete 20 the structure is locked olf by a simple severing of each endof each tendon 12 iat 22 below its supporting beam. Immediately thestress previously exerted upon the blockwalls 15 is transferred throughthe adhesion of the concrete Wall 20 to the end portions of the tendons12 to the concrete wall 20 while being maintained across the floor 10 ofthe pool. lPre-stressing of the concrete walls 20 is thus provided for.

The above described method may be varied in several ways while retainingthe novel basic conception of the invention. In place of the blockwalls15 some other form of support may be provided to retain the tensionedcondition of the tendons during pouring of the concrete walls. Removableplates may serve this purpose, as well as functioning as formwork forthe concrete walls. Locking-off may be achieved in one of many ways butpreferably this is done by cutting the individual tendons by anOxy-acetylene torch.

Whereas the invention has now been described with reference to apreferred embodiment it is to be understood that .modioation thereto isfeasible within its scope.

What I claim is:

1. A method of constructing a swimming pool having a floor andperipheral surrounding walls, comprising the steps of forming the oor bypreparing a bed for .the door, spreading moisture-proof sheeting overthe bed, laying one set of steel tendons in substantially parallel linesacross one dimension `of the -pool door and another set of steel tendonsin substantially parallel lines across another dimension of the poolfloor and substantially normal to the said first set, positioning a-plurality of guide sleeves around the rim of the intended oor for thepool through each of which an individual end portion of a tendon ispassed, said sleeves being anchored with respect to the oor and beingbent it-o direct the end portions of the tendons upwardly into the wallalignment rendering the portion of each tendon intermediate its endportions slidable with respect to the subsequent `concrete door, pouringthe concrete of the floor to cover the intermediate portions of thetendons and the guide sleeves, permit-ting the poured concrete to cure,constructing substantially upright cavity blockwalls around theperimeter of the pool floor, fastening one end of each tendon to anupper part of a respective blockw-all, applying strain to the other endof each tendon to impart stress to the concrete floor and fastening saidlast-mentioned end to an upper part of its respective blockwall whilethe tendon is under strain, pouring the concrete to form the Walls intothe cavity of the blockwalls and around the end portions of the tendons,permitting the concrete of the walls to cure, and cutting of the ends ofIthe tendons below their fastening points so that the stress in thetendons is transferred to the concrete walls while maintaining thestress on the concrete floor.

v2. A method according to claim 1, wherein a lubricant is applied tosaid intermediate portion of the ltendons before the concrete iioor ispoured to provide freedom for slip between the tendons and the concreteHoor.

3. A method of constructing a concrete reservoir for liquids having afloor and peripheral surrounding walls, comprising the steps of formingthe oor by preparing a bed for the Hoor, spreading moisture-proofsheeting over the bed, laying one set of steel tendons in substantiallyparallel lines across one dimension of the reservoir floor and anotherset of steel tendons in substantially parallel lines across anotherdimension of the reservoir oor and substantially normal to the saidfirst set, positioning a plurality of guide sleeves :around the rim ofthe intended floor for the reservoir through each of which an individualend portion of a tendon is passed, said sleeves being anchored withrespect to the oor and being bent to direct lthe end portions of theItendons upwardly into the wall alignment rendering the portion of eachtendon intermediate ,its end portions slidable with respect to thesubsequent concrete door, pouring :the concrete of the oor to cover theintermediate portions of the tendons and the guide sleeves, permittingthe poured concrete to cure, constructing substantially upright cavityblockwalls around the perimeter of the pool oor, straining said tendonsand fastening ends of said tendons to upper parts of respectiveblockwalls, pouring the concrete to form the walls into the cavity ofthe blockwalls and around the end portions of the tendons, permittingthe concrete of the Walls to cure, and cutting off the ends of thetendons below their fastening points so that the stress in the tendonsis transferred to the concrete walls While maintairb ing the stress onthe concrete floor.

References Cited UNITED STATES PATENTS 2,250,763 7/ 1941 Hild 52--426 XR2,655,846 10/ 1953 Freyssinet 52-230 XR 2,902,157 9/ 1959 Culver 52-223XR 3,060,640 10/ 1962 Harris 52-230 OTHER REFERENCES The Preload System,page 28, dated Nov. 23, 1942, by The Preload System C0., 1730 GrandCentral Terminal Building, New York.

HENRY C. SUTHERLAND, Primary Examiner.

P. C. FAW, Assistant Examiner.

